The present invention is directed generally to an anastomosis device. More particularly, the present invention is directed a paired, expandable device that joins one vessel to another.
An anastomosis is an operative union of two hollow or tubular structures. Anastomotic structures can be part of a variety of systems, such as the vascular system, the digestive system or the genitourinary system. For example, blood is shunted from an artery to a vein in an arteriovenous anastomosis, and from the right pulmonary artery to the superior vena cava in a cavopulmonary anastomosis. In other examples, afferent and efferent loops of jejunum are joined in a Braun""s anastomosis after gastroenteroscopy; the ureter and the Fallopian tube are joined in a ureterotubal anastomosis, and the ureter and a segment of the sigmoid colon are joined in a ureterosigmoid anastomosis. In microvascular anastomosis, very small blood vessels are anastomosed usually under surgical microscope.
An anastomosis is termed end-to-end when the terminal portions of tubular structures are anastomosed, and it is termed end-to-side when the terminal portion of a tubular structure is anastomosed to a lateral portion of another tubular or hollow structure. In an end-to-side anastomosis, we often refer to the structure whose end is anastomosed as the xe2x80x9cgraft vesselxe2x80x9d while the structure whose side wall is anastomosed is referred to as the xe2x80x9creceiving structurexe2x80x9d or xe2x80x9ctarget vesselxe2x80x9d.
The operative union of two hollow or tubular structures requires that the anastomosis be tight with respect to the flow of matter through such structures and also that the anastomosed structures remain patent for allowing an uninterrupted flow of matter therethrough. For example, anastomosed blood vessels should not leak at the anastomosis site, the anastomotic devices should not significantly disrupt the flow of blood, and the anastomosis itself should not cause a biological reaction that could lead to an obstruction of the anastomosed blood vessels. In particular, anastomosed blood vessels should remain patent and they should ideally not develop hyperplasia, thrombosis, spasms or arteriosclerosis.
Because anastomosed structures are composed of tissues that are susceptible to damage, the anastomosis should furthermore not be significantly detrimental to the integrity of these tissues. For example, injury to endothelial tissue and exposure of subintimal connective tissue should be minimized or even eliminated in vascular anastomosis.
Because structures to be anastomosed are internal, an anastomosis requires a degree of invasion. The invasive character of an anastomosis, however, should be minimized subject to the reliable performance of a satisfactory anastomosis. Accordingly, there has been a noticeable trend during the last quarter of this century towards less invasive surgical intervention, a surgical style that is termed minimally invasive surgery. This style is characterized by pursuing a maximal treatment effect with minimal damage to surrounding and overlying normal structures. In addition, successful minimally invasive procedures should procure patency and they should minimize damage to the tissues of the anastomosed structures themselves.
Particularly in the field of vascular anastomosis, it is acknowledged that there is an increasing demand for an easier, quicker, less damaging, but reliable procedure to create vascular anastomosis. This demand is further revitalized by the movement of vascular procedures towards minimally invasive procedures. See Paul M. N. Werker and Moshe Kon, Review of Facilitated Approaches to Vascular Anastomosis Surgery, Annals of Thoracic Surgery, Vol. 63 (1997) pp. S122-S127.
Anastomosis techniques generally intend to provide leak-proof joints that are not susceptible to mechanical failure, and they also intend to minimize damage and reduce the undesirable effects of certain operational features that may lead to post-anastomosis complications. Damage to be minimized and operational features whose undesirable effects should be reduced include endothelial coverage injury, exposure of subintimal connective tissue, exposure of an intraluminal foreign component, blood flow interruption, irregularities at the junction, adventitial tissue stripping, intimal injury, installment of a foreign rigid body, use of materials that may have toxic effects, damage to surrounding tissue, extensive vessel eversion, and tissue plane malalignment. A common feature of most conventional stapling, coupling and clipping techniques, particularly when applied to small-diameter vessels, is that they require a temporary interruption of the blood stream in the recipient vessel. As the instrumentation that is needed at the anastomosis site becomes complex and cumbersome, a wider open area is needed for accessing the anastomosis site, thus leading to an increasingly invasive procedure.
Post-anastomosis complications include neointimal hyperplasia, atherosclerosis, thrombosis, stenosis, tissue necrosis, vascular wall thinning, and aneurism formation. In particular, potential for thrombosis and for other complications is increased when the anastomosis site does not expand and contract with systole and diastole, causing flow disturbances as blood crosses the anastomosis. Therefore, a flexible and expandable anastomosis device that responds to changing blood pressure during systole and diastole is needed to decrease the potential for thrombosis and other complication.
Potential for flow disturbance at the anastomosis site is also increased when the opening at the anastomosis site has a relatively small diameter. Of course, it is desirable to minimize the size of instruments utilized to form the anastomosis. Smaller instruments minimize the intrusiveness of the procedure. What is needed, therefore, is an anastomosis device that expands upon release and stretches the tissue at the anastomosis opening, enabling the anastomosis to have a larger diameter than the initial anastomosis opening.
Also needed is an anastomosis device that acts external to vessels without penetrating at least one of the vessels and that creates an anastomosis more quickly than conventional techniques, with minimal interruption of blood flow.
It is an object of the present invention to provide a device for joining vessels together that minimizes complications such as thrombosis through the use of expandable rings that expand and contract with changes in fluid flow through the vessel after anastomosis is complete.
It is a further object of the present invention to provide an anastomosis device that avoids restriction of the lumen at the anastomosis by radially expanding upon deployment, thus minimizing complications such as thrombosis.
Additionally, another object of the invention is to provide an anastomosis device that joins vessels together through the use of expandable rings that are guided to each other by guides.
A further objection of this invention is to provide devices for joining vessels together in a secure manner such that the portions defining the openings of the vessels are not penetrated.
A further object of this invention to provide an anastomosis device that efficiently and reliably joins two vessels together at an anastomosis site.
The present invention is a paired, expandable anastomosis device that joins one vessel opening to another vessel opening. The anastomosis device has two rings. Referred to herein as first and second rings. In one embodiment each ring is made of connected flexible segments. Each flexible segment has two arms that are hingedly connected to form expandable V-shaped segments.
One embodiment of the anastomosis device has a ring is designed so that a portion of a target vessel can be everted through and held on the ring during the anastomosis procedure. The other ring of this embodiment is designed so that a portion of a graft vessel can be everted through and held on the ring during the anastomosis procedure.
Each ring has a holding surface, such as a plurality of holding tabs, to hold the everted vessel tissue. Holding tabs are preferably configured with rounded tips to avoid penetrating the vessel walls. The holding tabs of the ring used to anchor the graft vessel on the ring may have barbs or hooks to more securely hold the graft vessel.
The holding tabs in each ring are preferably oriented relative to the holding tabs of the opposing ring so that when the rings are brought together, each one of the holding tabs in a rings is opposite the space between two neighboring holding tabs in the opposing ring. When the rings are brought together so that the tips of the holding tabs enter or at least close to entering the opposing spaces between the holding tabs of the other ring, the everted tissue will be held together, creating a secure anastomosis.
Once the target and graft vessels are loaded onto the anastomosis device, the rings are guided together. Several embodiments are discussed that enable the rings to be guided together. In one embodiment, the anastomosis device includes a plurality of guides which guide the movement of one ring to the other ring. The rings may have a plurality of guides adapted to receive guideposts. The guides are preferably sized to frictionally engage the guideposts.
The rings have a loading position in which the vessels can be loaded onto the rings. In one embodiment, the guideposts of the second ring are completely inserted into the guides when in the loading position. The guideposts of the first ring are partially inserted into the guides so that the rings maintain an offset configuration. In this loading position, the holding tabs of the first ring are sufficiently spaced from the holding tabs of the second ring so that the graft vessel can be everted onto one ring and the target vessel can be everted onto the other ring. After the rings are loaded, they are brought together to create a secure anastomosis. The rings may be brought together manually or by the use of a device specifically designed for use with the rings, such as an attachment actuaction device. Once the rings are brought together, the frictional engagement of the guides and guideposts prevents the rings from inadvertently sliding on the guides.
The anastomosis device of the present invention provides an efficient, reliable anastomosis. Because the rings are expandable, the inventive anastomosis device minimizes complications caused with anastomosis devices of the prior art. Once the expandable rings are deployed to the anastomosis position, the rings permit the vessel tissue defining the anastomosis to expand and contract with expansion and contraction of the vessels. Additionally, the expandable rings radially expand to a deployed position when released from an external operator or tongs so that the vessel tissues defining the vessel openings are stretched to a diameter greater than the diameter of the initial opening in the target vessel. Also, no foreign material is placed in the interior of the vessel because the vessel tissue is everted onto the rings and the anastomosis is formed by bringing the everted interior of the graft vessel into contact with the everted, interior portion of the target vessel.